A lamp for producing a spectral light which is substantially identical in uniformity to the spectral light distribution of a desired daylight.
U.S. Pat. No. 5,666,017 describes a lamp for producing a spectral light which is substantially identical in uniformity to the spectral light distribution of a desired daylight throughout the entire visible light spectrum from about 380 to about 780 nanometers. The lamp contains a lamp envelope comprised of an exterior surface, a light-producing element substantially centrally disposed within said lamp envelope, and a coating on said exterior surface of said lamp envelope. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
U.S. Pat. No. 5,666,017 was a marked improvement over prior patent U.S. Pat. No. 5,418,419 because the former patent did not require the presence of a reflector; the entire disclosure of each of these United States patents (and of each of the United States patents mentioned in this specification) is hereby incorporated by reference into this specification. An equation used to specify the desired transmittance level of the coating at each wavelength was developed to describe the portion of the light that was directed at normal and non-normal incidence towards the coating. The portion of light normally incident upon the lamp envelope was considered to have a high probability of exiting the envelope with the desired daylight qualities with the reflected portion having a high probability of being reflected back to the filament, absorbed and re-emitted. The non-normal light on the other hand was considered to have a high probability of exiting the lamp at levels that varied from the desired daylight spectrum and the reflected portion having a low probability of being directed back to the filament and instead finding its way out of the lamp cavity through multiple reflections.
It is an object of this invention to provide an improved daylight lamp in which a greater portion of the light exiting the lamp simulates daylight.
It is another object of this invention to provide an improved daylight lamp in which the light produced more accurately simulates daylight.
It is yet another object of this invention to provide a daylight lamp which produces better uniformity in its spectral output using a single reflector and multiple cover glasses.
It is yet another object of this invention to produce a daylight lamp which produces multiple daylight outputs and/or beamspreads.
In accordance with this invention, there is provided an improved lamp for producing a spectral light which is substantially identical in uniformity to the spectral light distribution of a desired daylight throughout the entire visible light spectrum from about 380 to about 780 nanometers. The lamp contains a lamp envelope comprised of an exterior surface, a light-producing element substantially centrally disposed within said lamp envelope, and a coating on said exterior surface of said lamp envelope.